Cable knife



Patented July 7, 1931 PATENT OFFICE MELVIN r. TOLES, or lemon, u'rmOABLE KNIFE Application filed December 19, 1928. Serial No. 327,059.

This invention relates to devices for cutting wire ropes or cables suchas those used in drilling oil and other wells.

One of the objects of the invention is to i provide an improved devicefor cutting wire ropes or cables such as are generally used in 4 oil andgas well operations when the drilling tools supported by the cablesbecome lodged in the well in such a manner that they cannot be withdrawnby a pull upon the cable to which they are attached.

Another object ofthe invention is to provide a device of this characterin which a keen edged cutting element is actuated into cuttingengagement with the cable by the force exerted by the firing of aconfined explosive.

Still another object of the invention is to provide a cable cuttingdevice wherein the cutting element is normally maintained out of contactwith the cable so as to permit free movement of the device up and downthe cable.

Other objects, features and advantages of the invention will appear fromthe follow- 25 ing description taken in connection with the accompanyingdrawings in which:

Figure 1 is a vertical sectional view of the device taken generally online 11 of Figure 3.

Figure 2 is a vertical sectional view in general similar to that ofFigure 1, but showing the cutting element after having severed thecable.

Figure 3 is a sectional plan view taken on line 33 of Figure 1, and

Figure 4 is a sectional plan View taken on line 4-4 of Figure 1.

Referring to the drawings, there is illustrated a section of a wellcasing 10 through which a wire cable 11 extends. The cable 11 isattached to a socket 12 carrying the usual string of drilling tools (notshown). It is when these drilling tools become lodged 1n the well thatit is necessary to use my cutting tool to sever the cable 11 at a pointadjacent the socket 12 in order to clear the way for the use of suitablefishingiltools with which to dislodge and remove t e drilling tools.

The cutting device com rises an elongated cylindrical body 13 form witha central longitudinal bore'or passage 14 of suiiicient diameter toprovide a sliding fit with the cable 11.

-' An eye 15 is secured on the upper end of body 13 to receive a cableor line 16 b means of which the device is lowered into t e well andwithdrawn from-the same after the cuttingoperation has been completed.

The body 13 is formed with a second lon tudinal bore or passage 17 whichextends su stantially the length of the body but curves inwardly nearthe lower end to intersect cable bore 14. The bore 17 is formed with twodiameters, the upper portion being of smaller diameter than the lowerportion.

The cable cutting element is disposed within bore 17 and consists of acurved and keen edged cutting member 18 which is pivotally connected tothe lower end of a connecting rod 19. The upper end of connecting rod 191s likewise pivotally connected to the lower end of a piston or plunger20, the diameter.

of which is such as to form a working fit yvzithin the upper restrictedportion of bore An annular flange 21 is formed intermediate the endsofthe. lower section of bore 17 and the upper surface of the flangeconstitutes a seat 22 for a coil spring 23 which surrounds a portion ofconnecting rod 19 and plunger 20. A ring 24 is secured on plunger 20 andis so positioned as to rest on the upper end of the coil 23. The weightof the cutter assembly thus resting on the spring is sufficient tomaintain the latter under compression.

The compression under which the string is maintained normally forces theassembly of cutter, connecting rod and plunger upwardly within bore 17,as is clearly shown in Figure 1. In this position the cutter 18 isentirely within bore 17 and out of contact with cable 11.

A hollow plug 25 is screwed into the upper end of bore 17. The plug isadapted to hold or contain a percussion cap 26 and the wall of the boretogether with the space between the upper end of plunger 20 and thelower end of lug 25 form a chamber 27 which is adapte to be completelyfilled with an explosive mixture such, for example, as gun pow- 5:

der. A-hole or opening 28 is provided in the wall of body 13 and isadapted to connect the chamber 27 with the atmosphere.

'Body 13 is formed with still another longitudinal bore 01' passage 29in which a firin rod 30 is slidably mounted. The firing ro extendsbeyond the two ends of the body and is prevented from dropping throughthe bore by means of a collar 31 secured near its upper end. The collaris of greater diameter than bore 29 and may either rest upon the upperface ofthe body or, as shown, be seated within a recess 32 formedbycslightly enlarging the bore at its upper end.

The upper end of firing rod 30 is adapted to make contact with thelongarm 33 of a fulcrumed rocker arm 33 which is pivotally mounted in abracket 34 secured on the upper face of body 13. The short arm 33 isprovided with a firing pin 35 which is adapted to make contact with cap26, when actuated by firing rod 30, to fire the cap and, in turn, causethecombustion of the powder within chamber 27 Assuming that a well isbeing drilled with the usual drilling tools and that the tools become solodged that they cannot be removed by pulling the cable 11, it thenbecomes necessary to resort to the use of fishing tools to dislodge andremove the drilling tools. This necessitates cutting the drilling cable11 at a.

point near the tool socket 12, and the removal of the cable from thewell in order to make way for free use of the fishing tools.

In order to sever the cable 11 my im roved device is first put inreadiness for use y filling the chamber 27 with gun powder or an-. othersuitable explosive and screwing the plug 25, with its percussion cap 26,in place. When ready for use the parts are in the position shown inFigure 1, with the coil spring 23 holding the cutting member 18 wellwithin' the bore 17.

The next step is to slip the device over the upper end of the cable 11and then to lower it into the well by means of the cable 16. As will beseen the firing arm 30 extends below the lower end of body 13 and as thedevice descends into the well the end of the firing arm will eventuallymake contact with socket 12. If the device is lowered 1nto the well withsufiicient speed the impact between the firing arm 30 and the socket 12will be enough to give an upward thrust to the firing arm, the upper endof which Wlll then ac.- tuate the rocker arm 33 so as to force thepercussion cap 26. This sudden contact will cause the cap to explode andthe fire caused by the explosion will ignite the powder wlthin thechamber 27. The sudden burning of the powder within the limits of thechamber 27 will cause a sudden increase in pressure which will actuatethe plunger 20 1n a downward direction much as does the explosion of-tacting of said firing pin 35 into suddent contact with the too acartrid e in a gun ex 1 a bullet. The en-- tire cuttin assembly 1s thusforced downwardly un er great ressure and the cutting member 18 isguided by the curved wall at the lower end of bore 17 into cuttingengagement with the cable 11. With a sufiicient charge of ex losive inthe chamber 27 the force exerte through the connecting rod 20 willbesuflicientto completely sever the cable with a single operation. Theforce of the ex losion projects the plunger downwardly an opens the holeor opening 28 to the atmosphere so that the pro ucts of the combustionmay escape from the chamber 27. The parts will be in the o moment tliecable 11 is severed.

As soon as pressure is relieved within the chamber the coil spring 23,the compression of which has been greatly increased, will immediatelyforce the cutting assembly upwardly within the bore 17 until the partsagain assume their original position. The device can then be withdrawnfrom the well by a pull on cable 16 and the fishing tools can then einserted toefl'ect the removal of the drilling tools.

.A device of preferred form and construction has been illustrated anddescribed for the purpose of showing a way in which this invention maybe practiced, but the inventive thought upon-which this application isbased is broader than this illustrative embodiment thereof. It is,therefore, understoodthat the scope of the invention is not to belimited by the present disclosure, reference being bad to the appendedclaims for that'purpose.

What I claim is:

1 A device for severing a drill cable from a tool socket comprising abody formed with a longitudinal bore for the (lllll cable and a secondbore intersecting the cable bore, a

cable cutting member in said second bore, an-

explosive in said second bore, and impact controlled means forcontrolling the projection of the cutting member by said explosive intocutting engagement with the drill cable.

2. A device for severing a drill cable from a tool socket comprisin abody formed with a longitudinal bore and a second bore intersecting thefirst bore, a keen-edged member normally disposed within said secondbore, a member slidable wit 'n said body and rojecting below the lowerend thereof, an explosive means rendered effective upon theconprojecting member with the 1 socket for actuating the keen-edgedmember into cutting engagement with the drill cable.

3. In a device for severing a drill cable, a body member ada ted toslide on the drill cable, a keen-edge member movably mounted within saidbod a chambered member in said body adapte to contain an ex losivemixture, and means slidably mounted 1n said upon the cutting member 18-bod adapted to efiect the combustion of said exp osive mixture foractuating the keenedged member into cutting engagement with the drillcable. I 4. In a device for severing a drill cable from a tool socket, abody member formed with a bore for the drill cable, a second boreintersecting the cable bore, a keen-edged member normally maintained insaid second bore, a plunger in said second bore and operativelyconnected with the keen-edged member, a plu removably secured in theupper end of sai second bore, the space between the lower end of theplug and the upper end of 16 the plunger bein adapted to be filled withan explosive, a r slidably mounted in said body and extending beyond theends thereof, and means rendered effective upon the contacting of therod with the tool socket for ef- 20 fecting the combustion of the exlosive to actuate the plunger and thereby impel the keen-edged memberinto cutting engagement with the cable.

5. In a device for severing a cable a body formed with a longitudinalbore or said cable, a cable cuttin member mounted in said body, meansinc uding a charge of explosive for actuating said cutting member tosever said cable, and means energized upon 7 striking a predeterminedfixed object for igniting said explosive. 6. A cable cutting devicecomprising a body formed with a longitudinal bore for the cable, akeen-edged cutting member mounted in said body, explosive means forpropelling said cuttin member to out said cable, and impactcontro ledmeans for actuating said explosive means.

In witness whereof I have hereunto set my 4 hand this 7th day ofDecember 1928.

MELVIN h. TOLES.

